1. Field of the Invention
This invention relates to forward looking infrared camera systems and, more specifically, to a system and method for increasing the resolution in the scan direction of a camera using a multicolumn focal plane array detector.
2. Brief Description of Prior Art
The present generation of forward looking infrared camera systems that use focal plane array (FPA) detectors has a problem displaying moving objects. Such cameras sample the field of view in one scan per frame with 960 detectors at a 30 Hertz frame rate. The TV monitor that displays the scanned image operates at 30 Hertz frame rate, 60 Hertz field rate, 2 to 1 interlaced. To generate this format, the video processor splits the scanned frame into two fields, each field having half of the information obtained during a single scan, and presents the fields at a 60 Hertz rate on a standard TV monitor. When operating in accordance with this procedure, a moving object being scanned appears to flicker on the TV monitor. This flicker exists because the TV monitor displays the moving target twice during a frame in the same screen location, but one-half frame duration or one field time apart. The next frame presents the target in the same manner with the displacement accumulated due to motion during a full frame time, fooling the observer into seeing momentarily two stationary objects separated in space. Since each object disappears from the TV monitor after a single frame, the moving object appears to jump or flicker. The flicker is not present if the forward looking infrared (FLIR) system both scans and displays the image at the same frequency. Standard 60 Hertz TV monitors have too much flicker over the entire picture when operated at 30 Hertz and the detector cannot sample the image with sufficient speed to operate at a 60 Hertz scan rate without reducing the resolution. Further, the present FPA has two limitations that reduce resolution at 60 Hertz in that the minimum time between samples is 12.8 microseconds and all of the detector elements are sampled at the same time.